Apparatus And Method For Reducing A Transient Signal In A Magnetic Field Sensor

ABSTRACT

A magnetic field sensor includes a compensation loop coupled in series with normal circuit couplings in order to reduce a transient signal that would otherwise be generated when the magnetic field sensor experiences a high rate of change of magnetic field. In some embodiments, the magnetic field sensor is a current sensor responsive to a magnetic field generated by a current-carrying conductor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of and claims the benefitof U.S. patent application Ser. No. 12/900,969, filed Oct. 8, 2010,which is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

FIELD OF THE INVENTION

This invention relates generally to magnetic field sensors and, moreparticularly, to a magnetic field sensor that includes features that canreduce a transient signal that would otherwise be generated when themagnetic field sensor is in the presence of a rapidly changing magneticfield.

BACKGROUND OF THE INVENTION

As is known magnetic field sensors can be used in a variety ofapplications. In one application, a magnetic field sensor can be used tosense an electrical current. One type of current sensor uses a Halleffect magnetic field sensing element in proximity to a current-carryingconductor. The Hall effect magnetic field sensing element generates anoutput signal having a magnitude proportional to the magnetic fieldinduced by the current through the conductor. Typical current sensors ofthis type include a gapped toroid magnetic flux concentrator, with theHall effect device positioned in a toroid gap. The Hall effect deviceand toroid are assembled in a housing, which is mountable on a printedcircuit hoard. In use, a separate current-carrying conductor, such as awire, is passed through the center of the toroid and is soldered to theprinted circuit board, such as by soldering exposed ends of the wire toplated through-holes.

Other configurations of current sensors that use magnetic field sensingelements are known. Other configurations of current sensors aredescribed in U.S. Pat. No. 6,781,359, issued Aug. 24, 2004 and U.S. Pat.No. 7,265,531, issued Sep. 4, 2007, both of which are assigned to theassignee of the present invention and both of which are incorporated byreference herein in their entireties.

Various parameters characterize the performance of current sensors,including sensitivity, which is the change in the output signal of acurrent sensor in response to a one ampere change through the conductor,and linearity, which is the degree to which the output signal of acurrent sensor varies in direct proportion to the current through theconductor. Important considerations in magnetic field sensors includethe effect of stray magnetic fields and external magnetic noise on thesensor performance.

It has been observed that an output signal from a magnetic field sensor,for example, a current sensor, tends to have a transient “glitch” whenthe magnetic field sensor is exposed to a very high rate of change ofmagnetic field, for example, as may be generated by a very high rate ofchange of current in a current-carrying conductor. The source of thisglitch has not been understood.

Techniques, such as filters, have been employed to remove this unwantedglitch. However, filters tend to slow down a desired edge rate otherwiseavailable at the output of a magnetic field sensor.

It would be desirable to provide a magnetic field sensor, for example, acurrent sensor, which does not have the undesired glitch in the outputsignal when exposed to a rapidly changing magnetic field (or current).

SUMMARY OF THE INVENTION

The present invention provides a magnetic field sensor, for example, acurrent sensor, which does not have the undesired glitch in the outputsignal when exposed to a rapidly changing magnetic field (or current).

In accordance with one aspect of the present invention, a magnetic fieldsensor includes a lead frame having a base plate, a ground pin coupledto the base plate, and a signal output pin. The magnetic field sensoralso includes a circuit die disposed upon the base plate. The circuitdie includes a substrate. The circuit die also includes a magnetic fieldsensing element disposed upon the substrate and configured to generate amagnetic field signal responsive to a magnetic field. The circuit diealso includes an output circuit disposed upon the substrate. The outputcircuit includes a circuit ground node and a circuit output node. Theoutput circuit is configured to generate an output signal at the circuitoutput node responsive to the magnetic field signal. The circuit diealso includes a ground circuit trace having first and second ends. Thefirst end of the ground circuit trace is coupled to the circuit groundnode. The circuit die also includes a ground bonding pad coupled to thesecond end of the ground circuit trace. The circuit die also includes anoutput signal circuit trace having first and second ends. The first endof the output signal circuit trace is coupled to the circuit outputnode. The circuit die also includes an output signal bonding pad coupledto the second end of the output signal circuit trace. The magnetic fieldsensor further includes a circuit loop. The circuit loop includes aconductive path between the ground pin and the signal output pin. Thecircuit loop has a circuit loop interior area. The magnetic field sensorfurther includes a compensated signal output node coupled to the circuitoutput node. The magnetic field sensor further includes a conductivestructure, which includes a compensation loop coupled in a seriesarrangement with the circuit loop. The compensation loop has acompensation loop interior area. The compensation loop interior area isselected to be related to the interior area of the circuit loop. A pathtraversing the circuit loop in a direction from a first end of theseries arrangement to a second end of the series arrangement has acircuit loop rotation direction opposite from a compensation looprotation direction traversing the compensation loop along the same path.The compensation loop interior area and the compensation loop rotationdirection are selected to result in a reduction of an overshoot or anundershoot of an output signal at the compensated signal output noderesulting from the circuit loop experiencing a rapid change in flux ofthe magnetic field.

In some embodiments, the compensation loop is coupled between thecircuit output node and the compensated signal output node or thecompensation loop is coupled between the between a loop termination nodeand the ground node.

In accordance with another aspect of the present invention, in amagnetic field sensor having a lead frame having a ground pin and asignal output pin, the magnetic field sensor also comprising a circuitdie disposed upon the lead frame and comprising a magnetic field sensingelement and an output circuit coupled to the magnetic field sensingelement, wherein the output circuit comprises a circuit ground node anda circuit output node, a method of compensating an output signal in themagnetic field sensor responsive to a magnetic field includesidentifying a circuit loop in the magnetic field sensor. The circuitloop includes a conductive path between the ground pin and the signaloutput pin. The circuit loop has a circuit loop interior area. Themethod also includes providing a compensated signal output node coupledto the circuit output node. The method also includes providing aconductive structure. The providing the conductive structure includesproviding a compensation loop coupled in a series arrangement with thecircuit loop. The compensation loop has a compensation loop interiorarea selected to be related to the interior area of the circuit loop. Apath traversing the circuit loop in a direction from a first end of theseries arrangement to a second end of the series arrangement has acircuit loop rotation direction opposite from a compensation looprotation direction traversing the compensation loop along the same path.The compensation loop interior area and the compensation loop rotationdirection are selected to result in a reduction of an overshoot or anundershoot of an output signal at the compensated signal output noderesulting from the circuit loop experiencing a rapid change in flux ofthe magnetic field.

In some embodiments, providing the compensation loop comprises providingthe compensation loop coupled between the circuit output node and thecompensated signal output node or providing the compensation loopcoupled between the between a loop termination node and the ground node.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention, as well as the invention itselfmay be more fully understood from the following detailed description ofthe drawings, in which:

FIG. 1 is a pictorial showing a current sensor having a U-shaped fluxconcentrator;

FIGS. 2 and 2A are block diagrams showing two views of anotherembodiment of a current sensor having a donut shaped flux concentrator;

FIG. 3 is a graph showing a magnetic field of the current sensors ofFIG. 1, 2 or 2A along an x direction;

FIG. 3A is a graph showing a magnetic field of the current sensors ofFIG. 1, 2, or 2A along a y direction;

FIG. 4 is a block diagram of circuitry that can be included in thecurrent sensors of FIG. 1, 2, or 2A, the block diagram showing aso-called circuit loop and showing a so-called compensation loop;

FIGS. 4A-4C are pictorial diagrams showing two loops, looping inopposite directions, coupled in a variety of series arrangements;

FIG. 5 is block diagram showing a circuit loop occurring in a prior artmagnetic field sensor, here in a current sensor;

FIG. 6 is a graph showing a rapidly changing current sensed by the priorart current sensor of FIG. 5;

FIG. 6A is a graph showing a rapidly changing output signal generated bythe prior art current sensor of FIG. 5 when experiencing the rapidlychanging current of FIG. 6, showing an unwanted transient signalportion;

FIG. 6B is a graph showing a rapidly changing current sensed by acurrent sensor of the present invention;

FIG. 6C is a graph showing a rapidly changing output signal generated bythe current sensor of the present invention when experiencing therapidly changing current of FIG. 6B, showing no unwanted transientsignal portion or a reduced amplitude transient signal portion;

FIG. 7 is block diagram showing a circuit die having a compensation loopon a signal side of an output amplifier;

FIG. 7A is block diagram showing a circuit die having a compensationloop on a ground side of an output amplifier;

FIG. 8 is a block diagram showing the circuit die of FIG. 7 coupled to alead frame in an integrated circuit package;

FIG. 8A is a block diagram showing the circuit die of FIG. 7A coupled toa lead frame in an integrated circuit package;

FIG. 9 is a block diagram showing a circuit die, for example, thecircuit die of FIG. 5, coupled to a lead frame in an integrated circuitpackage, wherein the lead frame includes a compensation loop on a signalside of an output amplifier;

FIG. 9A is a block diagram showing a circuit die, for example, thecircuit die of FIG. 5, coupled to another lead frame in an integratedcircuit package, wherein the lead frame includes a compensation loop ona signal side of an output amplifier;

FIG. 9B is a block diagram showing a circuit die, for example, thecircuit die of FIG. 5, coupled to yet another lead frame in anintegrated circuit package, wherein the lead frame includes acompensation loop on a ground side of an output amplifier;

FIG. 10 is a block diagram showing a circuit die, for example, thecircuit die of FIG. 5, coupled to yet another lead frame in anintegrated circuit package, wherein the integrated circuit package iscoupled to a circuit board, wherein the circuit board includes acompensation loop on the signal side of an output amplifier;

FIG. 10A is a block diagram showing a circuit die, for example, thecircuit die of FIG. 5, coupled to yet another lead frame in anintegrated circuit package, wherein the integrated circuit package iscoupled to a circuit board, wherein the circuit board includes acompensation loop on the ground side of an output amplifier;

FIGS. 11 and 11A are block diagrams showing two views of a circuit diecoupled to yet another lead frame in an integrated circuit package,wherein the lead frame includes a compensation loop on a signal side ofan output amplifier, and wherein the compensation loop has bends totransition to a plane below a base plate of the lead frame;

FIGS. 12 and 12A are block diagrams showing two views of a circuit diecoupled to yet another lead frame in an integrated circuit package,wherein the integrated circuit includes a circuit board having acompensation loop on a signal side of an output amplifier;

FIG. 13 is a side view of a circuit die coupled to a lead frame with adirect bonding method, coupled with solder balls or the like; and

FIG. 13A is a side view of a circuit die coupled to a lead frame with adirect bonding method in a relative flip-chip arrangement, coupled withsolder balls or the like.

DETAILED DESCRIPTION OF THE INVENTION

Before describing the present invention, some introductory concepts andterminology are explained. As used herein, the term “magnetic fieldsensing element” is used to describe a variety of electronic elementsthat can sense a magnetic field. The magnetic field sensing elements canbe, but are not limited to, Hall effect elements, magnetoresistanceelements, or magnetotransistors. As is known, there are different typesof Hall effect elements, for example, a planar Hall element, a verticalHall element, and a circular Hall element. As is also known, there aredifferent types of magnetoresistance elements, for example, a giantmagnetoresistance (GMR) element, an anisotropic magnetoresistanceelement (AMR), a tunneling magnetoresistance (TMR) element, an Indiumantimonide (InSb) sensor, and a magnetic tunnel junction (MTJ).

As is known, some of the above-described magnetic field sensing elementstend to have an axis of maximum sensitivity parallel to a substrate thatsupports the magnetic field sensing element, and others of theabove-described magnetic field sensing elements tend to have an axis ofmaximum sensitivity perpendicular to a substrate that supports themagnetic field sensing element. In particular, most types ofmagnetoresistance elements tend to have axes of maximum sensitivityparallel to the substrate and most types of Hall elements tend to haveaxes of sensitivity perpendicular to a substrate.

As used herein, the term “magnetic field sensor” is used to describe acircuit that includes a magnetic field sensing element. Magnetic fieldsensors are used in a variety of applications, including, but notlimited to, a current sensor that senses a magnetic field generated by acurrent carried by a current-carrying conductor, a magnetic switch thatsenses the proximity of a ferromagnetic object, a rotation detector thatsenses passing ferromagnetic articles, for example, magnetic domains ofa ring magnet, and a magnetic field sensor that senses a magnetic fielddensity of a magnetic field.

While magnetic field sensors having Hall effect elements are shown anddescribed in examples below, the same techniques can be applied to amagnetic field sensor having any type of magnetic field sensing element.

Current sensors are shown and described in examples, below. However, thesame techniques can be applied to any magnetic field sensor, and,desirably, to any magnetic field sensor that experiences a rapid rate ofchange in a magnetic field.

Current sensors with flux concentrators are shown and described inexamples below. It will be understood that the use of a fluxconcentrator tends to increase the rate of change of a magnetic fieldexperienced by the magnetic field sensor. While this increase tends toresult in large output signal transients described below, for example,in conjunction with FIGS. 6 and 6A, techniques described below can beapplied to any magnetic field sensor, with or without a fluxconcentrator.

Referring to FIG. 1, an integrated current sensor 10, shown in anexploded view prior to final assembly, includes a magnetic field sensingelement, here in the form of Hall effect magnetic sensor 12 (here shownwithout an encapsulated body for clarity), a current-carrying conductor16 and a magnetic core 24. The conductor 16 includes features forreceiving portions of the Hall effect sensor 12 and the magnetic core 24such that the elements are maintained in a fixed and aligned positionrelative to each other.

In the illustrated embodiment, the conductor 16 has a first notch 18 aand a second notch 18 b substantially aligned with the first notch. Whenassembled, at least a portion of the Hall effect sensor 12 is disposedin the first notch 18 a. The magnetic core 24 is substantially C-shaped(or U-shaped) and has a central region 24 a and a pair of substantiallyparallel legs 24 b, 24 c extending from the central region. Whenassembled, at least a portion of the central region 24 a is disposed inthe second notch 18 b of the conductor 16 such that each leg 24 b, 24 ccovers at least a portion of a respective surface of the Hall effectsensor 12.

In some embodiments, the conductor 16, and, in particular, the notches18 a, 18 b, are formed by stamping.

The Hall effect sensor 12 is provided in the form of an integratedcircuit containing a sensor die 14 having a Hall effect element 14 athereon, all encapsulated with an electrically insulating material. Theintegrated Hall effect sensor 12 can be provided in different packagetypes, such as the “K” single in line (SIP) package having a thicknesson the order of 1.6 mm. The effective air gap is equal to the thicknessof the package, with the sensor die resting approximately in the centerof the air gap.

The Hall effect sensor has leads 15 adapted for mounting to a printedcircuit board (not shown). Leads 15 include a power, or Vcc, connection,a ground connection, and an output connection adapted to carry an outputsignal proportional to the current through the conductor 16. The outputsignal can be a current or a voltage.

The sensor die 14 includes the Hall effect element 14 a and Hallcircuitry 14 b for processing the output signal of the Hall effectelement 14 a. Use of the Hall effect sensor 12 enhances the integrationof the current sensor 10 by incorporating circuit components whichotherwise would be provided separately, such as by discrete componentsmounted to a printed circuit board.

The conductor 16 can be comprised of various conductive materials, suchas copper, and is adapted for mounting to a printed circuit boardthrough which the measured current is provided to the conductor 16. Tothis end, bent leads or tabs 16 a, 16 b (16 b not shown) suitable forsoldering into circuit board vias (or holes) are provided at endportions of the conductor 16. Mechanisms other than bent tabs 16 a, 16 bmay be used to mount the current sensor 10 to a circuit hoard, such asscrew terminals and associated hardware or flat leads or tabs. Inalternate embodiments, the same or other mounting mechanisms can be usedto allow the current sensor 10 to be mounted to other than a circuitboard. For example, the current sensor 10 can have wire couplings (notshown) that allow the current sensor 10 to be coupled in series with awire.

Preferably, the conductor 16 (excluding the bent tabs 16 a, 16 b) issubstantially planar as shown, without features extending in the z-axis21 which would increase the height of the current sensor 10 off of theprinted circuit board. In use, the plane of the conductor 16 ispositioned close to the printed circuit board plane, thereby providing alow profile current sensor.

The first notch 18 a of the conductor 16 has a width w2 selected toreceive at least a portion of the Hall effect sensor 12, which has awidth w1. Preferably, the width w1 and the width w2 are sufficientlysimilar so that, in assembly, the possible movement of the Hall effectsensor 12 relative to the conductor 16 in the x-axis 19 is negligible.More specifically, nominal width w1 is slightly smaller than nominalwidth w2, such as by approximately 0.28 mm, so that, with worst casetolerances, the largest width w1 is 0.4 mm smaller than the smallestwidth w2. In the illustrated embodiment, nominal width w1 is 5.18 mm andnominal width w2 is 5.46 mm. Widths w1 and w2 can thus be characterizedas being substantially equal.

The second notch 18 b of the conductor has a width w3 selected toreceive at least a portion of the magnetic core 24. Preferably, thewidth w3 and the width w4 of the central region 24 a of the magneticcore are sufficiently similar, so that, in assembly, the possiblemovement of the magnetic core 24 relative to the conductor 16 in thex-axis 19 is negligible. More specifically, nominal width w4 is slightlysmaller than nominal width w3, such as by approximately 0.2 mm, so that,with worst case tolerances, the smallest width w4 is 0.34 mm smallerthan the largest width w3 and the largest width w4 is 0.08 mm smallerthan the smallest width w3, in the illustrated embodiment, nominal widthw3 is 5.46 mm and nominal width w4 is 5.25 mm. Widths w3 and w4 can thusbe characterized as being substantially equal.

The spacing h3 between magnetic core legs 24 b, 24 c, the thickness orheight h2 of the conductor 16 and the thickness or height h1 of the Halleffect sensor 12 are all substantially similar so that possible movementof the components relative to each other in the z-axis 21 is restricted.More specifically, nominal conductor height h2 and sensor height h1 areslightly smaller than nominal height h3, such as by approximately 0.1mm, so that, with worst case tolerances, the smallest height h1 andheight h2 are 0.22 mm smaller than the largest height h3 and the largestheight h1 and height h2 are 0.01 mm smaller than the smallest height h3.In the illustrated embodiment, the nominal height h1 is 1.55 mm, thenominal height h2 is 1.50 mm, and the nominal height h3 is 1.64 mm.

In other embodiments, however, the spacing h3 is selected in accordancewith other factors. For example, in one alternate embodiment, thespacing h3 is substantially larger than the height h1 of the Hall effectsensor 12, in order to increase the reluctance and, therefore, toincrease the current through the carrying conductor 16 that wouldsaturate the current sensor 10. Thus, this alternate embodiment has agreater current carrying capacity.

The magnetic core 24 tailors the magnetic field across the sensor die 14and may be referred to alternatively as a magnetic field concentrator, amagnetic flux concentrator, or simply as a flux concentrator. Themagnetic core 24 may be comprised of various materials including, butnot limited to ferrite, steel, iron compounds, and permalloy. Thematerial of the magnetic core 24 is selected based on factors such asmaximum measured current, which is related to a magnetic permeability ofthe core 24, and the desired amount of magnetic shielding provided bythe magnetic core 24. Other factors include stability of the relativepermeability over temperature and hysteresis (magnetic remanence). Forexample, a low hysteresis ensures greater accuracy for small currentsthrough the conductor 16. The material and size of the magnetic core 24are also selected in accordance with the desired full scale currentthrough the conductor 16, wherein a magnetic core material with a highersaturation flux density (Bsat) allows the use of a smaller core for agiven current flowing through the conductor 16. As will become apparentfrom consideration of FIG. 4 below, use of the magnetic core 24significantly reduces the susceptibility of the current sensor 10 tostray magnetic fields.

The magnetic core 24 has a depth d1, selected so that each of the legs24 b, 24 c substantially covers an entire respective surface of thesensor die 14. With this arrangement, a substantially uniform magneticfield is provided across the Hall effect element 14 a disposed on thesensor die 14, thereby increasing device sensitivity and reducingsusceptibility to stray magnetic fields.

Here, the conductor notch 18 a is formed by tabs 16 d, 160 extendingradially outward from the conductor. Notch 18 b is formed by a narrowedregion 16 c of the conductor in combination with tabs 16 f, 16 gextending from the conductor. The width w5 of the narrowed region 16 ebetween the first and the second notches 18 a, 18 b is selected based onthe maximum current carrying capability of the electrical conductor 16.In some embodiments, the width w5 is on the order 1.7 mm and the currentcarrying capability of the conductor 16 is on the order of 100 Amperes.Although the notches 18 a, 18 b could be formed by radial tabs 16 d, 16e, and 16 f, 16 g respectively, without providing the narrowed conductorregion 16 c, the use of the narrowed region 16 e minimizes the overalldimension of the current sensor 10 along the y-axis 20. The narrowedregion also provides the current through the conductor 16 in closerproximity to the Hall effect sensor 12. In an alternate embodiment, thenotches 18 a, 18 b are formed without the tabs 16 d-16 g, and areprovided only by the narrowed region 16 e.

It will be understood that the current carrying conductor 16, whenpassing a current, will cause a relatively large magnetic field at theHall effect element 14 a, larger than if the flux concentrator 24 werenot used. Furthermore, it will become apparent from discussion below inconjunction with FIGS. 3 and 3A that the magnetic field at the Halleffect element 14 a will be relatively uniform over a large area in xand y directions 19, 20, respectively, more uniform than if the fluxconcentrator 24 were not used.

Referring now to FIGS. 2 and 2A, another embodiment 50 of a currentsensor 50 includes a donut shaped flux concentrator 52 having a notch orcutout 56 therein and a central hole 54. A magnetic field sensor 58having a Hall effect element 58 a and leads 60 can be disposed in thenotch 56.

It will be understood that a current carrying conductor (not shown)positioned to pass through the hole 54, when passing a current, willcause a relatively large magnetic field at the Hall effect element 58 a,larger than if the flux concentrator 52 were not used. Furthermore, itwill become apparent from discussion below in conjunction with FIGS. 3and 3A that the magnetic field at the Hall effect element 58 a will berelatively uniform over a large area in x and y directions 62, 64,respectively, more uniform than if the flux concentrator 52 were notused.

Referring to FIG. 3, a graph 80 illustrates the magnetic flux densityalong the x-axis 19 of the Hall effect element 14 a of FIG. 1 or alongthe x-axis 62 of the Hall effect element 58 a of FIGS. 2 and 2A whenabout one hundred Amperes is passed through the conductor 16 of FIG. 1or through the conductor (not shown) passing through the hole 56 ofFIGS. 2 and 2A. A center of the Hall effect element 14 a (FIG. 1) or ascenter of the Hall effect element 58 a (FIGS. 2, 2A) corresponds to zeromillimeters on the x-axes 19, 62.

A magnetic flux curve 86 can be characterized as having a centralportion 88 that is essentially flat and inclined end portions 90 a, 90b. Consideration of the curve 86 reveals that the magnetic flux issubstantially constant in the central portion 88 for a span on the orderof 4 mm centered about the centers of the Hall effect elements 14 a, 58a. Portions of the Hall effect elements 14 a, 58 a located more than 2mm from their centers along the x-axes 19, 62 experience reducedmagnetic flux density. The illustrative Hall effect elements 14 a, 58 ahave an x-axis width on the order of 0.2 mm, centered on sensor dietypically having dimensions of approximately 1.6 mm by 3 mm, andtherefore, the entire Hall effect elements 14 a, 58 a lie in the centralportion 88. The width of the central portion 88 is substantially greaterthan the width of the Hall effect elements 14 a, 58 a, and the Halleffect elements 14 a, 58 a are sufficiently centered within the centralportion 88 to ensure that the Hall effect elements 14 a, 58 a are withinthe greatest amount of magnetic field.

It will be appreciated that the dimensions of the magnetic cores 24, 52relative to the Hall effect elements 14 a, 58 a affect the uniformity ofthe flux density across the Hall effect elements 14 a, 58 a in thedirection of the x-axes 19, 62. In particular, the wider the magneticcore 24 (i.e., the greater the width w4), relative to the width of theHall effect element 14 a in the x direction 19, and the thicker the fluxconcentrator 52 in the x direction 62 relative to a width of the Halleffect element 58 a in the x direction 62, the longer the centralportion 88 of the curve 86, whereas, the narrower the magnetic core, theshorter the central portion 88.

Curve 86 presumes that the magnetic cores 24, 52 and Hall effectelements 14 a, 58 a are centered relative to one another in the xdirections 19, 62, respectively. Movement of the Hall effect elements 14a, 58 a relative to the magnetic cores 24, 52 along the x-axes 19, 62would result in the curve 86 moving along the axis 84 and thus, resultin areas of the Hall effect elements 14 a, 58 a even closer to theircenters than 2 mm, experiencing significantly reduced flux density. Thiseffect highlights the desirability of restricting relative movement ofthe Hall effect sensors 12, 58 and the magnetic cores 24, 52. Further,since there is a tolerance associated with the location of the Halleffect elements 14 a, 58 a within the Hall effect sensors 12, 58,respectively, fixing the position of the Hall effect sensors 12, 58relative to the magnetic cores 24, 52 is important.

Referring now to FIG. 3A, a graph 100 illustrates the magnetic fluxdensity along the y-axes 20, 64 of the Hall effect elements 14 a, 58 awhen about one hundred Amperes is passed through the conductor 16 ofFIG. 1 or through the conductor (not shown) passing through the hole 54of FIGS. 2 and 2A. A center of the Hall effect elements 14 a, 58 acorresponds to zero millimeters on the axis 104.

A magnetic flux curve 106 can be characterized as having a centralportion 108 that is essentially flat and inclined end portions 110 a,110 b. Consideration of the curve 106 reveals that the magnetic flux issubstantially constant in the central portion 108 for a span on theorder of 2.5 mm centered about the center the Hall effect elements 14 a,58 a. Portions of the Hall effect elements 14 a, 58 a located more than1.25 mm from their centers along the y-axes 20, 64 experience reducedmagnetic flux density. The illustrative Hall effect elements 14 a, 58 ahave a y-axis width on the order of 0.2 mm, centered on sensor dietypically having dimensions of approximately 1.6 mm by 3 mm, andtherefore the entire Hall effect elements 14 a, 58 a lie in the centralportion 108. The width of central portion 108 is substantially greaterthan the width of the Hall effect element 14 a, 58 a, and the Halleffect elements 14 a, 58 a are sufficiently centered within the centralportion 108 to ensure that the Hall effect elements 14 a, 58 a arewithin the greatest amount of magnetic field.

It will be appreciated that the dimensions of the magnetic cores 24, 52relative to the Hall effect elements 14 a, 58 a significantly affect theuniformity of the flux density across the Hall effect elements 14 a, 58a in the direction of the y-axes 20, 64. In particular, the deeper themagnetic cores 24, 52 in the y directions 20, 64, relative to the widthof the Hall effect elements 14 a, 58 a, the longer the central portion108 of the curve 106, whereas, the shallower the magnetic core, theshorter the central portion 108.

Curve 106 presumes that the magnetic cores 24, 52 and Hall effectelements 14, 58 a are centered relative to one another in the ydirections 20, 64. Movement of the Hall effect elements 14 a, 58 arelative to the magnetic cores 24, 52 along the y-axes 20, 64 wouldresult in the curve 106 moving along the axis 104 and thus, result inareas of the Hall effect elements 14 a, 58 a, even closer to theircenters than 1.25 mm, experiencing significantly reduced flux density.This effect again highlights the desirability of restricting relativemovement of the Hall effect sensor 12, 58 relative to the magnetic cores24, 52.

Referring now to FIG. 4, in which like elements of FIG. 1 are shownhaving like reference designations, a schematic representation of theexemplar). Hall effect current sensor 10 of FIG. 1 includes theconductor 16 represented by a line having circuit board mountingmechanisms 16 a, 16 b, and the magnetic core 24 here represented by atorpid 162. While the representation of FIG. 4 is described inconjunction with FIG. 1, it will be understood that the same descriptionand circuits can apply to the magnetic field sensor 50 of FIGS. 2-2A.The illustrative Hall effect sensor 12 includes the sensor die 14 andleads 15, here labeled 15 a, 15 b, and 15 c. Lead 15 a provides a powerconnection to the Hall effect current sensor 12, lead 15 b provides aconnection to the current sensor output signal, and lead 15 c provides areference, or ground connection to the current sensor.

The Hall effect element 14 a senses a magnetic field 164 induced by acurrent flowing in the conductor 16, producing a voltage in proportionto the magnetic field 164. The Hall effect element 14 a is coupled to adynamic offset cancellation circuit 170, which provides a DC offsetadjustment for DC voltage errors associated with the Hall effect element14 a. When the current through the conductor 16 is zero, the output ofthe dynamic offset cancellation circuit 170 is adjusted to be zero.

The dynamic offset cancellation circuit 170 is coupled to an amplifier172 that amplifies the offset adjusted Hall output signal. The amplifier172 is coupled to a filter 174 that can be a low pass filter, a highpass filter, a band pass filter, and/or a notch filter. The filter isselected in accordance with a variety of factors including, but notlimited to, desired response time, the frequency spectrum of the noiseassociated with the Hall effect element 14 a, the dynamic offsetcancellation circuit 170, and the amplifier 172. In one particularembodiment, the filter 174 is a low pass filter. The filter 174 iscoupled to an output driver 176 that provides an enhanced power outputfor transmission to other electronics (not shown).

A trim control circuit 184 is coupled to lead 15 a through which poweris provided during operation. Lead 15 a also permits various currentsensor parameters to be trimmed, typically during manufacture. To thisend, the trim control circuit 184 includes one or more counters enabledby an appropriate signal applied to the lead 15 a.

The trim control circuit 184 is coupled to a quiescent output voltage(Qvo) circuit 182. The quiescent output voltage is the voltage at outputlead 15 b when the current through conductor 16 is zero. Nominally, fora unipolar supply voltage, Qvo is equal to Vcc/2. Qvo can be trimmed byapplying a suitable trim signal through the lead 15 a to a first trimcontrol circuit counter within the trim control circuit 184 which, inturn, controls a digital-to-analog converter (DAC) within the Qvocircuit 182.

The trim control circuit 184 is further coupled to a sensitivityadjustment circuit 178. The sensitivity adjustment circuit 178 permitsadjustment of the gain of the amplifier 172 in order to adjust thesensitivity of the current sensor 10. The sensitivity can be trimmed byapplying a suitable trim signal through the lead 15 a to a second trimcontrol circuit counter within the trim control circuit 184 which, inturn, controls a DAC within the sensitivity adjustment circuit 178.

The trim control circuit 184 is further coupled to a sensitivitytemperature compensation circuit 180. The sensitivity temperaturecompensation circuit 180 permits adjustment of the gain of the amplifier172 in order to compensate for gain variations due to temperature. Thesensitivity temperature compensation can be trimmed by applying asuitable trim signal through the lead 15 a to a third trim controlcircuit counter within the trim control circuit 184 which, in turn,controls a DAC within the sensitivity temperature compensation circuit180.

An output signal from the output driver 176 experiences two conductiveloops in conjunction with its path from the output driver to the signaloutput pin 15 b. A first loop 190, referred to herein as a “circuitloop,” has a first rotation direction indicated by an arrow, and asecond loop 192, referred to herein as a “compensation loop,” has asecond different and opposite rotation direction indicated by anotherarrow. The circuit loop 190 is described more fully below in conjunctionwith FIG. 5. The compensation loop is described more fully below inconjunction with FIGS. 7-12B.

Let it suffice here to say that the circuit loop 190 is naturallyoccurring in the sensor die 14 due to layout of circuits on the circuitdie 14. The circuit loop 190 tends to generate a transient signal whenthe circuit loop directly experiences a rapid change of magnetic fieldas may be generated by a rapid change of current passing through theconductor 16. The compensation loop 192 is a physical conductive loophaving a variety of configurations that can be provided to cancel orreduce the transient signal that forms as a result of the circuit loop190.

It will be appreciated that the circuitry shown in FIG. 4 isillustrative only of exemplary circuitry that may be associated with andintegrated into a Hall effect current sensor, like the Hall effectcurrent sensor 10 of FIG. 1. In another embodiment, additional circuitrymay be provided for converting the current sensor into a “digital fuse”which provides a high or low output signal depending on whether themagnetic field 164 induced by the current through the conductor 16 isgreater or less than a predetermined threshold level. The additionalcircuitry for this alternative embodiment can include a comparatorand/or a latch, and/or a relay. An exemplary embodiment of a digitalfuse is shown in FIG. 7.

Further, since the conductor connections 16 a, 16 b are electricallyisolated from the current sensor leads 15 a, 15 b, and 15 c, the currentsensor 10 can be used in applications requiring electrical isolationwithout the use of opto-isolators or other isolating techniques, such astransformers.

Referring now to FIG. 4A, the two loops 190, 192 of FIG. 4 are againshown but with better clarity. The two loops are coupled in a seriesarrangement, a path from left to right rotating counterclockwise in thefirst loop and the path rotating clockwise in the second loop. Both ofthe loops are shown to be closed loops.

Referring now to FIG. 4B, two different loops are shown and are againcoupled in a series arrangement. The loops are open loops. As usedherein, the term “loop” refers to both open loops and to closed loops,and more particularly, to any conductor that takes any curved paththrough any number of degrees, for example, bending through ninetydegrees.

As in FIG. 4B, a path from left to right rotates counterclockwise in thefirst loop and the path rotates clockwise in the second loop.

Referring now to FIG. 4C, two different loops are again coupled in aseries arrangement, a second loop intermediate to the first loop.

A path from left to right rotates counterclockwise in a first portionthe first loop, the path rotates clockwise in the second loop, and thepath rotates counterclockwise again in a second portion the first loop.It will, therefore, be understood that the term “series arrangement”when referring to a coupling of two loops can be a coupling of theloops, one after the other, or a coupling wherein a second loop isintermediate to the first loop.

While the path through the first loop is shown to rotatecounterclockwise and the path through the second loop is shown to rotateclockwise, the reverse is also possible. Also, while rotations indifferent direction are shown, and such is the case in embodiments shownbelow as will be apparent, series connected loops can also have pathsthat rotate in the same direction.

In FIGS. 5 and 7-12B below, magnetic field sensor are shown without fluxconcentrators for clarity. However, preferably, all of the magneticfield sensors of FIGS. 5 and 7-12B include a respective fluxconcentrator, for example, a flux concentrator having the form of one ofthose shown in FIGS. 1, 2, and 2A.

Referring now to FIG. 5, a magnetic field sensor 200 is shown without aflux concentrator. The magnetic field sensor 200 can include a circuitdie 203 and a lead frame 240 disposed within a molded package 202. Thecircuit die 203 can include a Hall effect element 204 configured togenerate a magnetic field signal carried on a conductor 206. The signalcarried by the conductor 206 is responsive to a current 244 flowingthrough a conductor 242 disposed near to the Hall effect element 204.Interface circuits 208 are coupled to receive the magnetic field signalcarried by the conductor 206 and configured to generate an interfacesignal carried by a conductor 210. An output amplifier (or buffer) 212is coupled to receive the interface signal carried on the conductor 210.The interface circuits 208 and the output amplifier 212 will be readilyunderstood from the above discussion in conjunction with FIG. 4.

The output amplifier 212 includes a circuit ground node 216 and acircuit output node 218. The circuit output node 218 is coupled to thecircuit ground node 216 via an internal resistance 214 within the outputamplifier 212.

A ground circuit trace 228 has first and second ends, wherein the firstend of the ground circuit trace 228 is coupled to the circuit groundnode 216. A ground bonding pad 220 is coupled to the second end of theground circuit trace 228. An output signal circuit trace 230 has firstand second ends, wherein the first end of the output signal circuittrace 230 is coupled to the circuit output node 218. An output signalbonding pad 222 is coupled to the second end of the output signalcircuit trace 230.

A signal bond wire 232 is coupled between the output signal bonding pad222 and a signal output pin 236. Which is part of the lead frame 240. Aground bond wire 226 is coupled between the ground bonding pad 220 and aground node 234 on a base plate 241, which is part of the lead frame240, which is coupled to a ground pin 238, which is part of the leadframe 240.

The ground bond wire 226, the ground circuit trace 228, the resistance214, the output signal circuit trace 230, and the output signal bondwire 232 form parts of a so-called “circuit loop” 234, shown as a dashedline. The circuit loop 234 can be symbolically closed by way of ahorizontal line shown at the lower perimeter of the molded package 202.

It will be understood that a conductive loop tends to form a voltage atends thereof in response to a rapidly changing magnetic field as may begenerated by the current 244 when rapidly changing. The voltage tends toresult in a transient and unwanted signal shown and described below inconjunction with FIGS. 6 and 6A.

The generated voltage in a loop is described by Faraday's Law:

V=−N(dΦ/dt)

where:

N is the number of turns of a loop

Φ is magnetic flux; and

dΦ/dt is a rate of change of magnetic flux.

It will be understood that:

Φ=BA if B is uniform and perpendicular to a plan of the loop

where:

-   -   B is flux density; and    -   A is area of the loop. (Note that, for an open loop, the area        can be found by connecting the ends of the loop with a line, for        example, a straight line.)

Thus, the induced voltage in a loop is proportional to a rate of changeof magnetic flux, related to a number of turns of the loop, and relatedto an area of the loop.

As shown, the circuit loop 234 is bounded within a rectangle that isabout 3 mm×about 1.5 mm. The circuit loop, which does not fill theentire rectangular area, has a circuit loop interior area that is about3.6 square millimeters. A path traversing the circuit loop 234 in adirection from the ground pin 238 to the signal output pin 236 has acircuit loop rotation direction, which can be counterclockwise as shown,or which can be clockwise in other arrangements.

It will be understood that the boundaries of the circuit loop, found byinspection of an irregular shape, may not be entirely correct. Thus,there may be one or more trial and error circuit die fabricationattempts to establish the area of the circuit loop.

Referring now to FIG. 6, a graph 250 has a horizontal axis in units oftime in microseconds and a vertical axis in units of electrical currentin Amperes. A signal 252 has a transition region representative of arapidly changing current as may be carried by the conductor 242 of FIG.5.

Referring now to FIG. 6A, a graph 260 has a horizontal axis in units oftime in microseconds and a vertical axis in units of voltage in volts.In response to the current signal 252 of FIG. 6, a signal 262 isrepresentative of an output signal as may be generated at the outputsignal pin 236 of FIG. 5. The signal 262 has an unwanted transientsignal portion 264, not representative of the current signal 252 of FIG.6, shown as a downward transition coincident with the onset of thetransition region of the signal 252 of FIG. 6.

It has been recognized by the invention herein that the transient signalportion 264 is generated by the circuit loop 234 of FIG. 5 as itexperiences a high rate of change of magnetic field (or a high rate ofchange of magnetic flux). In other words, the transient signal portion264 is generated as a result of a physical conductive loop at or nearthe output amplifier of the magnetic field sensor 200 of FIG. 5.

As described above, others have attempted to remove the transient signal264 by way of is filters or the like. However, these techniques tend toslow down a response rate of the signal 262. It has not been previouslyknown that the transient signal is the result of the above-describedcircuit loop as it experiences a high rate of change of magnetic field.

Referring now to FIG. 6B, the graph 250 of FIG. 6 is again shown.

Referring now to FIG. 6C, a graph 270 has a horizontal axis in units oftime in microseconds and a vertical axis in units of voltage in volts.In response to the current signal 252 of FIG. 6B, a signal 272 isrepresentative of an output signal as may be generated at an output pinof circuits shown and described below, which include a compensation loopcoupled in series with the circuit loop 234 of FIG. 5. The signal 262has no transient signal portion like the transient signal portion 264 ofFIG. 6A.

Referring now to FIG. 7, a circuit die 300 can include a Hall effectelement 302 configured to generate a magnetic field signal carried on aconductor 304. Interface circuits 306 are coupled to receive themagnetic field signal carried by the conductor 304 and configured togenerate an interface signal carried by a conductor 308. An outputamplifier (or buffer) 310 is coupled to receive the interface signalcarried on the conductor 308.

The output amplifier 310 includes a circuit ground node 314 and acircuit output node 316. The circuit output node 316 is coupled to thecircuit ground node 314 via an internal resistance 312 within the outputamplifier 310.

A ground circuit trace 322 has first and second ends, wherein the firstend of the ground circuit trace 322 is coupled to the circuit groundnode 314. A ground bonding pad 318 is coupled to the second end of theground circuit trace 322.

An output signal circuit trace 324 has first and second ends, whereinthe first end of the output signal circuit trace 324 is coupled to thecircuit output node 316. An output signal bonding pad 320 is coupled tothe second end of the output signal circuit trace 324.

The output signal circuit trace 324, unlike the output signal circuittrace 230 of FIG. 5, takes a circular route in a “compensation loop” toreach the output signal bonding pad 320. A direction of the compensationloop 324 from the circuit output node 318 to the output signal bondingpad 320 (here clockwise) takes a direction opposite to theabove-described circuit loop 234 of FIG. 5.

It will be recognized that the compensation loop 324 is coupled in aseries arrangement with a circuit loop (not shown), which is the same asor similar to the circuit loop 234 of FIG. 5. Preferably, thecompensation loop 324 has an interior area about the same as theinterior area of the circuit loop 234 of FIG. 5.

It will be recognized that the compensation loop 324 and the circuitloop 234 of FIG. 5 have opposite rotation directions and tend to respondwith transient signals having opposite directions when the compensationloop 324 and the circuit loop 234 experience a large rate of change ofmagnetic field. Furthermore, if the compensation loop 324 and thecircuit loop 234 both have about the same interior area and if thecompensation loop 324 and the circuit loop 234 both experience about thesame rapidly changing magnetic field, then the compensation loop 324will tend to reduce or cancel the transient signal generated in thecircuit loop 234.

Particularly when using a flux concentrator proximate to the circuit die300, as will be apparent from the discussion above in conjunction withFIGS. 3 and 3A, the compensation loop 324 will tend to experience thesame magnetic field as the circuit loop 234. However, even if thecompensation loop 324 does not experience the same rapidly changingmagnetic field as the circuit loop 234 of FIG. 5, an area of thecompensation loop 324 or an area of the circuit loop 234 can be designedor adjusted accordingly to provide the cancellation or reductionresults.

The circuit die 300 is shown in FIG. 8 below when coupled into amagnetic field sensor, or more particularly, a current sensor.

Referring now to FIG. 7A, in which like elements of FIG. 7 are shownhaving like reference designations, a circuit die 350 can include theHall effect element 302 configured to generate the magnetic field signalcarried on the conductor 304. The interface circuits 306 are coupled toreceive the magnetic field signal carried by the conductor 304 andconfigured to generate the interface signal carried by the conductor308. The output amplifier (or buffer) 310 is coupled to receive theinterface signal carried on the conductor 303.

The output amplifier 310 includes the circuit ground node 314 and thecircuit output node 316. The circuit output node 316 is coupled to thecircuit ground node 314 via the internal resistance 312 within theoutput amplifier 310.

A ground circuit trace 352, which is longer than the ground circuittrace 322 of FIG. 7, has first and second ends, wherein the first end ofthe ground circuit trace 352 is coupled to the circuit ground node 314.A ground bonding pad 318 is coupled to the second end of the groundcircuit trace 352.

An output signal circuit trace 354, which is shorter than the outputsignal circuit trace 324 of FIG. 7, has first and second ends, whereinthe first end of the output signal circuit trace 354 is coupled to thecircuit output node 316. An output signal bonding pad 320 is coupled tothe second end of the output signal circuit trace 354.

The ground circuit trace 352, unlike the ground circuit trace 228 ofFIG. 5, takes a circular route in a “compensation loop” to reach theground bonding pad 318. A direction of the compensation loop 354 fromthe ground bonding pad 318 to the circuit ground node 314 (hereclockwise) takes a direction opposite to the above-described circuitloop 234 of FIG. 5.

It will be recognized that the compensation loop 352 is coupled in aseries arrangement with a circuit loop (not shown), which is the same asor similar to the circuit loop 234 of FIG. 5. Preferably, thecompensation loop 352 has an interior area about the same as theinterior area of the circuit loop 234 of FIG. 5.

It will be recognized that the compensation loop 352 and the circuitloop 234 of FIG. 5 have opposite rotation directions and tend to respondwith transient signals having opposite directions when the compensationloop 352 and the circuit loop 234 experience a large rate of change ofmagnetic field. Furthermore, if the compensation loop 352 and thecircuit loop 234 bath have about the same interior area and if thecompensation loop 352 and the circuit loop 234 both experience about thesame rapidly changing magnetic field, then the compensation loop 352will tend to reduce or cancel the transient signal generated in thecircuit loop 234.

Particularly when using a flux concentrator proximate to the circuit die350, as will be apparent from the discussion above in conjunction withFIGS. 3 and 3A, the compensation loop 352 will tend to experience thesame magnetic field as the circuit loop 234. However, even if thecompensation loop 352 does not experience the same rapidly changingmagnetic field as the circuit loop 234 of FIG. 5, an area of thecompensation loop 352 or an area of the circuit loop 234 can be designedor adjusted accordingly to provide the cancellation or reductionresults.

The circuit die 350 is shown in FIG. 8A below when coupled into amagnetic field sensor, or more particularly, a current sensor.

Referring now to FIG. 8, in which like elements of FIG. 7 are shownhaving like reference designations, the circuit die 300 of FIG. 7 iswithin a magnetic field sensor 400.

The magnetic field sensor 400 includes a lead frame 420 having a baseplate 418, a ground pin 416 coupled to the base plate 420, and a signaloutput pin 414. The magnetic field sensor 400 includes the circuit die300 of FIG. 7 disposed upon the base plate 418. The circuit die 300includes a substrate 301. The circuit die 300 also includes the magneticfield sensing element 302 disposed upon the substrate 301 and configuredto generate a magnetic field signal responsive to a magnetic field(e.g., a magnetic field generated by a current 404 flowing in aconductor 402). The circuit die 301 also includes the output circuit 310disposed upon the substrate 301. The output circuit 310 includes thecircuit ground node 314 and the circuit output node 316. The outputcircuit 310 is configured to generate an output signal at the circuitoutput node 316 responsive to the magnetic field signal. The circuit die301 also includes the ground circuit trace 322 having first and secondends. The first end of the ground circuit trace 322 is coupled to thecircuit ground node 314. The circuit die also includes the groundbonding pad 318 coupled to the second end of the ground circuit trace322. The circuit die 301 also includes the output signal circuit trace324 having first and second ends. The first end of the output signalcircuit trace 324 is coupled to the circuit output node 316. The circuitdie 301 also includes the output signal bonding pad 320 coupled to thesecond end of the output signal circuit trace 324. The magnetic fieldsensor 400 further includes a circuit loop 234 (FIG. 5). The circuitloop 234 includes a conductive path between the ground pin 416 and thesignal output pin 414. The circuit loop 234 has a circuit loop interiorarea. The magnetic field sensor 400 further includes a compensatedsignal output node 412 coupled to the circuit output node 316. Themagnetic field sensor 400 further includes a conductive structure, whichincludes a compensation loop 324 coupled in a series arrangement withthe circuit loop 234 (FIG. 5). The compensation loop 324 has acompensation loop interior area. The compensation loop interior area isselected to be related to the interior area of the circuit loop 234.Also, a path traversing (see, e.g., arrow 422) the circuit loop 234 in adirection from a first end of the series arrangement to a second end ofthe series arrangement has a circuit loop rotation direction oppositefrom a compensation loop rotation direction traversing the compensationloop along the same path. The compensation loop interior area and thecompensation loop rotation direction are selected to result in areduction of an overshoot or an undershoot of an output signal at thecompensated signal output node 412 resulting from the circuit loop 234experiencing a rapid change in flux of the magnetic field.

In the embodiment of FIG. 8, the compensation loop 324 is coupledbetween the circuit output node 316 and the compensated signal outputnode 414, i.e., on the signal side of the circuit loop 234. Thecompensation loop 324 is the same as the signal circuit trace 324.

Referring now to FIG. 8A, in which like elements of FIGS. 7A and 8 areshown having like reference designations, the circuit die 350 of FIG. 7Ais within a magnetic field sensor 430, i.e., on a signal side of thecircuit loop 234.

The magnetic field sensor 430 includes the lead frame 420 having thebase plate 418, the ground pin 416 coupled to the base plate 420, andthe signal output pin 414. The magnetic field sensor 430 includes thecircuit die 350 of FIG. 7A disposed upon the base plate 418. The circuitdie 350 includes a substrate 351. The circuit die 350 also includes themagnetic field sensing element 302 disposed upon the substrate 351 andconfigured to generate a magnetic field signal responsive to a magneticfield (e.g., a magnetic field generated by the current 404 flowing inthe conductor 402). The circuit die 351 also includes the output circuit310 disposed upon the substrate 351. The output circuit 310 includes thecircuit ground node 314 and the circuit output node 316. The outputcircuit 310 is configured to generate an output signal at the circuitoutput node 316 responsive to the magnetic field signal. The circuit die351 also includes the ground circuit trace 352 having first and secondends. The first end of the ground circuit trace 352 is coupled to thecircuit ground node 314. The circuit die 351 also includes the groundbonding pad 318 coupled to the second end of the ground circuit trace352. The circuit die 351 also includes the output signal circuit trace354 having first and second ends. The first end of the output signalcircuit trace 354 is coupled to the circuit output node 316. The circuitdie also includes the output signal bonding pad 320 coupled to thesecond end of the output signal circuit trace 354. The magnetic fieldsensor 430 further includes a circuit loop 234 (FIG. 5). The circuitloop 234 includes a conductive path between the ground pin 416 and thesignal output pin 414. The circuit loop 234 has a circuit loop interiorarea. The magnetic field sensor 430 further includes the compensatedsignal output node 412 coupled to the circuit output node 316. Themagnetic field sensor 430 further includes a conductive structure, whichincludes a compensation loop 352 coupled in a series arrangement withthe circuit loop 234 (FIG. 5). The compensation loop 352 has acompensation loop interior area. The compensation loop interior area isselected to be related to the interior area of the circuit loop 234(FIG. 5). Also, a path traversing (see, e.g., arrow 422) the circuitloop 234 in a direction from a first end of the series arrangement to asecond end of the series arrangement has a circuit loop rotationdirection opposite from a compensation loop rotation directiontraversing the compensation loop along the same path. The compensationloop interior area and the compensation loop rotation direction areselected to result in a reduction of an overshoot or an undershoot of anoutput signal at a compensated signal output node 412 resulting from thecircuit loop 234 experiencing a rapid change in flux of the magneticfield.

In the embodiment of FIG. 8A, the compensation loop 352 is coupledbetween a loop termination node 408 and the ground node 314, i.e., onthe ground side of the circuit loop 234. The compensation loop 352 isthe same as the ground circuit trace 352.

Figures below present alternate structures that achieve theabove-described compensation loops, some on a signal side of the circuitloop 234 of FIG. 5, and others on the ground side.

Referring now to FIG. 9, a magnetic field sensor 500 includes a leadframe 542 having a base plate 540, a ground pin 538 coupled to the baseplate 540, and a signal output pin 536. The magnetic field sensor 500also includes a circuit die 508 disposed upon the base plate 540. Thecircuit die 508 includes a substrate 509. The circuit die 508 alsoincludes a magnetic field sensing element 503 disposed upon thesubstrate 509 and configured to generate a magnetic field signalresponsive to a magnetic field (e.g., a magnetic field generated by acurrent 504 flowing in a conductor 502). The circuit die 508 alsoincludes an output circuit 510 disposed upon the substrate 508. Theoutput circuit 510 includes a circuit ground node 512 and a circuitoutput node 514. The output circuit 510 is configured to generate anoutput signal at the circuit output node 514 responsive to the magneticfield signal. The circuit die 508 also includes a ground circuit trace520 having first and second ends. The first end of the ground circuittrace 520 is coupled to the circuit ground node 512. The circuit die 508also includes a ground bonding pad 516 coupled to the second end of theground circuit trace 520. The circuit die 508 also includes an outputsignal circuit trace 522 having first and second ends. The first end ofthe output signal circuit trace 522 is coupled to the circuit outputnode 514. The circuit die 508 also includes an output signal bonding pad518 coupled to the second end of the output signal circuit trace 522.The magnetic field sensor 500 further includes a circuit loop 234 (FIG.5). The circuit loop includes a conductive path between the ground pin538 and the signal output pin 536. The circuit loop 234 has a circuitloop interior area. The magnetic field sensor 500 further includes acompensated signal output node 534 coupled to the circuit output node514. The magnetic field sensor 500 further includes a conductivestructure, which includes a compensation loop 532 coupled in a seriesarrangement with the circuit loop 234. The compensation loop 532 has acompensation loop interior area. The compensation loop interior area isselected to be related to the interior area of the circuit loop. Also, apath (see, e.g., arrow 544) traversing the circuit loop 234 in adirection from a first end of the series arrangement to a second end ofthe series arrangement has a circuit loop rotation direction oppositefrom a compensation loop rotation direction traversing the compensationloop along the same path. The compensation loop interior area and thecompensation loop rotation direction are selected to result in areduction of an overshoot or an undershoot of an output signal at thecompensated signal output node 534 resulting from the circuit loopexperiencing a rapid change in flux of the magnetic field.

In the embodiment of FIG. 9, the compensation loop 532 is coupledbetween the circuit output node 514 and the compensated signal outputnode 534, i.e., on the signal side of the circuit loop 234.

The compensation loop 532 is farmed from a portion of the lead frame542, and in particular, a loop 532 between the signal output pin 536 anda blind pin 530. A bond wire 528 couples the signal output bonding pad518 to the blind pin 530. An insulator 546, for example, Kapton tape,can be disposed between the compensation loop 532 and the circuit die509.

It will be understood that, in this embodiment, the substrate 509 hangsoff of the base plate 540, and therefore, is subject to breakage whenthe wire bond 528 is bonded. However, the output signal bonding pad 518can be moved so as to be over the base plate 540 in order to reduce thechance of substrate breakage.

The magnetic field sensor is molded into a molded package 501. In somearrangements, a double molding process can be used to support thesubstrate 509 during the wire bonding of the wire bond 528. Doublemolding is further described below in conjunction with FIGS. 11 and 11A.

Referring now to FIG. 9A, in which like elements of FIG. 9 are shownhaving like reference designations, a magnetic field sensor 550 includesa lead frame 566 having a base plate 564, a ground pin 558 coupled tothe base plate 564, and a signal output pin 560. The magnetic fieldsensor 550 also includes the circuit die 508 of FIG. 9 disposed upon thebase plate 540. The circuit die 508 includes the substrate 509. Thecircuit die 508 also includes the magnetic field sensing element 503disposed upon the substrate 509 and configured to generate the magneticfield signal responsive to the magnetic field (e.g., the magnetic fieldgenerated by the current 504 flowing in the conductor 502). The circuitdie 508 also includes the output circuit 510 disposed upon the substrate508. The output circuit 510 includes the circuit ground node 512 and thecircuit output node 514. The output circuit 510 is configured togenerate the output signal at the circuit output node 514 responsive tothe magnetic field signal. The circuit die 508 also includes the groundcircuit trace 520 having first and second ends. The first end of theground circuit trace 520 is coupled to the circuit ground node 512. Thecircuit die 508 also includes the ground bonding pad 516 coupled to thesecond end of the ground circuit trace 520. The circuit die 508 alsoincludes the output signal circuit trace 522 having first and secondends. The first end of the output signal circuit trace 522 is coupled tothe circuit output node 514. The circuit die 508 also includes theoutput signal bonding pad 518 coupled to the second end of the outputsignal circuit trace 522. The magnetic field sensor 550 further includesthe circuit loop 234 (FIG. 5). The circuit loop 234 includes aconductive path between the ground pin 558 and the signal output pin560. The circuit loop 234 has a circuit loop interior area. The magneticfield sensor 550 further includes a compensated signal output node 562coupled to the circuit output node 514. The magnetic field sensor 550further includes a conductive structure, which includes a compensationloop 556 coupled in a series arrangement with the circuit loop 234. Thecompensation loop 556 has a compensation loop interior area. Thecompensation loop interior area is selected to be related to theinterior area of the circuit loop 234. Also, a path (see, e.g., arrow572) traversing the circuit loop 234 in a direction from a first end ofthe series arrangement to a second end of the series arrangement has acircuit loop rotation direction opposite from a compensation looprotation direction traversing the compensation loop along the same path.The compensation loop interior area and the compensation loop rotationdirection are selected to result in a reduction of an overshoot or anundershoot of an output signal at the compensated signal output node 562resulting from the circuit loop 234 experiencing a rapid change in fluxof the magnetic field.

In the embodiment of FIG. 9A, the compensation loop 556 is coupledbetween the circuit output node 514 and the compensated signal outputnode 562, i.e., on the signal side of the circuit loop 234 (FIG. 5).

The compensation loop 556 is formed from a portion of the lead frame566, and in particular, a loop 556 between the signal output pin 560 anda blind pin 554. A bond wire 552 couples the signal output bonding pad518 to the blind pin 554, and a bond wire 568 couples the ground bondingpad 516 to the base plate 564.

Unlike the magnetic field sensor 500 of FIG. 9, the magnetic fieldsensor 550 has the ground pin 558 in the center of the pins, resultingin the compensation loop 556 avoiding the base plate 564 and avoidingthe overhang of the substrate 509 as in FIG. 9.

Referring now to FIG. 9B, in which like elements of FIGS. 9 and 9A areshown having like reference designations, a magnetic field sensor 600includes a lead frame 620 having a base plate 618, a ground pin 614coupled to the base plate 618, and a signal output pin 616. The magneticfield sensor 600 also includes the circuit die 508 disposed upon thebase plate 618. The circuit die 508 includes the substrate 509. Thecircuit die 508 also includes the magnetic field sensing element 503disposed upon the substrate 509 and configured to generate the magneticfield signal responsive to the magnetic field (e.g., the magnetic fieldgenerated by the current 504 flowing in the conductor 502). The circuitdie 508 also includes the output circuit 510 disposed upon the substrate508. The output circuit 510 includes the circuit ground node 512 and thecircuit output node 514. The output circuit 510 is configured togenerate the output signal at the circuit output node 514 responsive tothe magnetic field signal. The circuit die 508 also includes the groundcircuit trace 520 having first and second ends. The first end of theground circuit trace 520 is coupled to the circuit ground node 512. Thecircuit die 508 also includes the ground bonding pad 516 coupled to thesecond end of the ground circuit trace 520. The circuit die 508 alsoincludes the output signal circuit trace 522 having first and secondends. The first end of the output signal circuit trace 522 is coupled tothe circuit output node 514. The circuit die 508 also includes theoutput signal bonding pad 518 coupled to the second end of the outputsignal circuit trace 522. The magnetic field sensor 600 further includesthe circuit loop 234 (FIG. 5). The circuit loop 234 includes aconductive path between the ground pin 614 and the signal output pin616. The circuit loop 234 has a circuit loop interior area. The magneticfield sensor 600 further includes a compensated signal output node 604coupled to the circuit output node 514. The magnetic field sensor 600further includes a conductive structure, which includes a compensationloop 610 coupled in a series arrangement with the circuit loop 234. Thecompensation loop 610 has a compensation loop interior area. Thecompensation loop interior area is selected to be related to theinterior area of the circuit loop 234. Also, a path (see, e.g., arrow622) traversing the circuit loop 234 in a direction from a first end ofthe series arrangement to a second end of the series arrangement has acircuit loop rotation direction opposite from a compensation looprotation direction traversing the compensation loop along the same path.The compensation loop interior area and the compensation loop rotationdirection are selected to result in a reduction of an overshoot or anundershoot of an output signal at the compensated signal output node 604resulting from the circuit loop 234 experiencing a rapid change in fluxof the magnetic field.

In the embodiment of FIG. 9B, the compensation loop 610 is coupledbetween a loop termination node 608 and the ground node 512, i.e., onthe ground side of the circuit loop 234 (FIG. 5).

The compensation loop 610 is formed from a portion of the lead frame620, and in particular, a loop 610 between the ground pin 614 and ablind pin 612. A bond wire 602 couples the signal output bonding pad 518to the signal output pin 616 and a bond wire 606 coupled the groundbonding pad 516 to the blind pin 612.

Referring now to FIG. 10, in which like elements of FIG. 9-9B are shownhaving like reference designations, a magnetic field sensor 674 includesan integrated magnetic field sensor 650 electrically coupled to acircuit board 675. The integrated magnetic field sensor 650 is like themagnetic field sensors 500, 550, 600 of FIGS. 9, 9A, 9B, respectively,but without any compensation loop. However, it will be understood thatthe integrated magnetic field sensor 650 includes the circuit loop 234of FIG. 5.

The magnetic field sensor 674 (i.e., the integrated magnetic fieldsensor 650) includes a lead frame 672 having a base plate 670, a groundpin 668 coupled to the base plate 670, and a signal output pin 666. Themagnetic field sensor 674 also includes the circuit die 508 of FIGS.9-9B disposed upon the base plate 670. The circuit die 508 includes thesubstrate 509. The circuit die 508 also includes the magnetic fieldsensing element 503 disposed upon the substrate 509 and configured togenerate the magnetic field signal responsive to the magnetic field(e.g., a magnetic field generated by a current 654 flowing in aconductor 652). The circuit die 508 also includes the output circuit 510disposed upon the substrate 508. The output circuit 510 includes thecircuit ground node 512 and the circuit output node 514. The outputcircuit 510 is configured to generate the output signal at the circuitoutput node 514 responsive to the magnetic field signal. The circuit die508 also includes the ground circuit trace 520 having first and secondends. The first end of the ground circuit trace 520 is coupled to thecircuit ground node 512. The circuit die 508 also includes the groundbonding pad 516 coupled to the second end of the ground circuit trace520. The circuit die 508 also includes the output signal circuit trace522 having first and second ends. The first end of the output signalcircuit trace 522 is coupled to the circuit output node 514. The circuitdie 508 also includes the output signal bonding pad 518 coupled to thesecond end of the output signal circuit trace 522. The magnetic fieldsensor 674 further includes the circuit loop 234 (FIG. 5). The circuitloop 234 includes a conductive path between the ground pin 668 and thesignal output pin 666. The circuit loop 234 has a circuit loop interiorarea. The magnetic field sensor 674 further includes a compensatedsignal output node 658 coupled to the circuit output node 514. Themagnetic field sensor 674 further includes a conductive structure, whichincludes a compensation loop 656 coupled in a series arrangement withthe circuit loop 234. The compensation loop 656 has a compensation loopinterior area. The compensation loop interior area is selected to berelated to the interior area of the circuit loop 234. Also, a path (see,e.g., arrow 676) traversing the circuit loop 234 in a direction from afirst end of the series arrangement to a second end of the seriesarrangement has a circuit loop rotation direction opposite from acompensation loop rotation direction traversing the compensation loopalong the same path. The compensation loop interior area and thecompensation loop rotation direction are selected to result in areduction of an overshoot or an undershoot of an output signal at thecompensated signal output node 658 resulting from the circuit loop 234experiencing a rapid change in flux of the magnetic field.

In the embodiment of FIG. 10, the compensation loop 656 is coupledbetween the circuit output node 514 and the compensated signal outputnode 658, i.e., on the signal side of the circuit loop 234 (FIG. 5).

The compensation loop 656 is formed by a conductive trace upon thecircuit board 675, in one or more conductive layers of the circuit board675. A bond wire 664 couples the signal output bonding pad 518 to thesignal output pin 666 and a bond wire 660 couples the ground bonding pad516 to the base plate 670.

The circuit board 675 can also include the conductor 652 as acurrent-carrying conductive trace configured to carry the current 654,wherein the magnetic field is generated in response to the current. Thecompensation loop 656 is disposed proximate to the conductor 652. Thecompensation loop 656 can be disposed at an edge of the conductor 652 sothat the magnetic field passes perpendicularly through the compensationloop 656.

The compensation loop 656 is shown here to include a plurality of nestedloops. Particularly when the compensation loop 656 is not under theinfluence of a flux concentrator, which is shown in FIGS. 1 and 2-2A,the compensation loop 656 will experience a smaller magnetic field thanmay be experienced by the circuit loop 234 (FIG. 5). Thus, in order tocompensate and reduce or cancel the transient signal of FIG. 6A, it maybe desirable to provide the compensation loop 656 with multiple loops asshown or with a larger area than the circuit loop 234 of FIG. 5.

Referring now to FIG. 10A, in which like elements of FIGS. 9-9B and 10are shown having like reference designations, a magnetic field sensor700 includes the integrated magnetic field sensor 650 of FIG. 10,electrically coupled to a circuit board 701. The integrated magneticfield sensor 650 is like the magnetic field sensors 500, 550, 600 ofFIGS. 9, 9A, 9B, respectively, but without any compensation loop.However, it will be understood that the integrated magnetic field sensor650 includes the circuit loop 234 of FIG. 5.

The magnetic field sensor 700 (i.e., the integrated magnetic fieldsensor 650) includes the lead frame 672 having the base plate 670, theground pin 668 coupled to the base plate 670, and a signal output pin666. The magnetic field sensor 700 also includes the circuit die 508 ofFIGS. 9-9B disposed upon the base plate 670. The circuit die 508includes the substrate 509. The circuit die 508 also includes themagnetic field sensing element 503 disposed upon the substrate 509 andconfigured to generate the magnetic field signal responsive to themagnetic field (e.g., a magnetic field generated by a current 706flowing in a conductor 704). The circuit die 508 also includes theoutput circuit 510 disposed upon the substrate 508. The output circuit510 includes the circuit ground node 512 and the circuit output node514. The output circuit 510 is configured to generate the output signalat the circuit output node 514 responsive to the magnetic field signal.The circuit die 508 also includes the ground circuit trace 520 havingfirst and second ends. The first end of the ground circuit trace 520 iscoupled to the circuit ground node 512. The circuit die 508 alsoincludes the ground bonding pad 516 coupled to the second end of theground circuit trace 520. The circuit die 508 also includes the outputsignal circuit trace 522 having first and second ends. The first end ofthe output signal circuit trace 522 is coupled to the circuit outputnode 514. The circuit die 508 also includes the output signal bondingpad 518 coupled to the second end of the output signal circuit trace522. The magnetic field sensor 700 further includes the circuit loop 234(FIG. 5). The circuit loop 234 includes a conductive path between theground pin 668 and the signal output pin 666. The circuit loop 234 has acircuit loop interior area. The magnetic field sensor 700 furtherincludes a compensated signal output node 667 coupled to the circuitoutput node 514. The magnetic field sensor 700 further includes aconductive structure, which includes a compensation loop 702 coupled ina series arrangement with the circuit loop 234. The compensation loop702 has a compensation loop interior area. The compensation loopinterior area is selected to be related to the interior area of thecircuit loop 234. Also, a path (see, e.g., arrow 710) traversing thecircuit loop 234 in a direction from a first end of the seriesarrangement to a second end of the series arrangement has a circuit looprotation direction opposite from a compensation loop rotation directiontraversing the compensation loop along the same path. The compensationloop interior area and the compensation loop rotation direction areselected to result in a reduction of an overshoot or an undershoot of anoutput signal at the compensated signal output node 667 resulting fromthe circuit loop 234 experiencing a rapid change in flux of the magneticfield.

In the embodiment of FIG. 10A, the compensation loop 702 is coupledbetween a loop termination node 708 and the ground node 512, i.e., onthe ground side of the circuit loop 234. The loop termination node canbe coupled to a reference voltage, for example, ground.

The compensation loop 702 is formed by a conductive trace upon thecircuit board 701, in one or more conductive layers of the circuit board701. The bond wire 664 couples the signal output bonding pad 518 to thesignal output pin 666 and the bond wire 660 couples the ground bondingpad 516 to the base plate 670.

The circuit board 674 can also include the conductor 704 as acurrent-carrying conductive trace configured to carry the current 706,wherein the magnetic field is generated in response to the current 706.The compensation loop 702 is disposed proximate to the conductor 704.

The compensation loop 702 is shown here to include a plurality of nestedloops. Particularly when the compensation loop 702 is not under theinfluence of a flux concentrator, which is shown in FIGS. 1 and 2-2A,the compensation loop 702 will experience a smaller magnetic field thanmay be experienced by the circuit loop 234 (FIG. 5). Thus, in order tocompensate and reduce or cancel the transient signal of FIG. 6A, it maybe desirable to provide the compensation loop 702 with multiple loops asshown or with a larger area than the circuit loop 234 of FIG. 5.

Comparing FIGS. 9 and 9A above, it will be apparent that is may bedifficult to provide a compensation loop formed as a part of a leadframe that does not interfere with the base plate of the lead frame.FIGS. 11 and 11A show another way for the compensation loop to avoid thebase plate.

Referring now to FIG. 11, a magnetic field sensor 800 includes a leadframe 830 having a base plate 832, a ground pin 828, and a signal outputpin 826. The lead frame 830 also includes a compensation loop 820coupled at one end to a blind pin 816 and at the other end to anotherblind pin 824. Transition regions 818, 822 (or bends) can depress thecompensation loop to be at a level below the base plate 832. Though notshown as such, the depression could be used to pass the compensationloop 820 under the base plate 832.

A ground bonding pad 812 is coupled to the base plate 832 with a bondwire 840. A signal output bonding pad 814 is coupled to the blind pin816 with a bond wire 834.

The blind pin 824 is coupled to a bonding pad 804 upon circuit die 802with a wire bond 838. The bonding pad 804 is coupled with a circuittrace 808 to an opposite side of the circuit die 802, to a bonding pad806. A bond wire 834 couples the bonding pad 806 to the signal outputpin 826 and to a compensation node 844.

The compensation loop 820 is shown to be coupled on an output signalside of a circuit loop 234 (FIG. 5). However, it will be understood thata similar compensation loop can be coupled on a ground side of thecircuit loop 234.

Referring now to FIG. 11A, in which like elements of FIG. 11 are shownhaving like reference designations, the compensation loop 830 is shownto be in a different plane than the base plate 832 by way of thetransition regions 818, 822. A first molded body 840 can be first formedto support the compensation loop and the base plate. A second moldedbody 842 can be formed in a second molding step to surround the firstmolded body 840, and the substrate 802.

Referring now to FIG. 12, another magnetic field sensor 850 can includea lead frame 872 having a base plate 874, a signal output pin 868, and aground pin 870 coupled to the base plate 874. A small circuit board 858can be disposed upon the base plate 874. The circuit board 858 caninclude a compensation loop 860 formed as a conductive trace upon thecircuit board 858. A circuit die 852 can be disposed upon the circuitboard 858. The circuit die 852 can include a ground bonding pad 854 anda signal output bonding pad 856. The signal output bonding pad 856 canbe coupled to one end of the compensation loop 860 with a bond wire 861.The other end of the compensation loop 860 can be coupled to the signaloutput pin 868 at a compensated signal output node 880 with a bond wire866. A bond wire 876 can couple the ground bonding pad 854 to the baseplate 874.

The compensation loop 860 is shown to be coupled on an output signalside of a circuit loop 234 (FIG. 5). However, it will be understood thata similar compensation loop can be coupled on a ground side of thecircuit loop 234.

Referring now to FIG. 12A, in which like elements of FIG. 12 are shownhaving like reference designations, the magnetic field sensor 850 caninclude one molded body 851.

Referring now to FIG. 13, whereas various circuit couplings to a signaloutput pin and to a ground pin are shown in prior figures to becomprised of wire bonds, in other embodiments, one or more of thecircuit couplings to a signal output pin 920 and to a ground pin 924 ofa lead frame 926 of any of the above-described magnetic field sensorscan instead be direct couplings comprised of solder balls 908, 916,coupled through soldering features 906, 914, respectively, and throughvias 904, 912, respectively, to bonding pads 902, 910, respectively,upon a substrate 900.

In the arrangement shown, the active side of the substrate 900 isdisposed upward such that an output amplifier 901 is disposed on a sideof the substrate 900 that is facing away from the lead frame 926.

While solder balls 908, 916 are shown, the direct bonding can be aselected one of a solder ball, a copper pillar, a gold bump, a eutecticand high lead solder bump, a no-lead solder bump, a gold stud bump, apolymeric conductive bump, an anisotropic conductive paste, or aconductive film coupled between the features 906, 914 and the lead framepins.

Referring now to FIG. 13A, direct couplings can instead be made betweena substrate 950 and a lead frame 970 (e.g., to pins 964, 968) relativelydisposed in a so-called “flip-chip” arrangement, such that an activesurface of the substrate 950 is disposed downward such that an outputamplifier 952 is disposed on a side of the substrate 950 that is facingtoward the lead frame 970. The direct couplings can be comprised ofsolder balls 956, 960, coupled between bonding pads 954, 958,respectively, and the lead frame pins 964, 968.

While solder balls 956, 960 are shown, the direct bonding can be aselected one of a solder ball, a copper pillar, a gold bump, a eutecticand high lead solder bump, a no-lead solder bump, a gold stud bump, apolymeric conductive bump, an anisotropic conductive paste, or aconductive film coupled between the bonding pads 954, 958 and the leadframe pins.

While compensation loops are shown in embodiments above to be generallydisposed on a signal side or on a ground side of the circuit loop 234 ofFIG. 5, in other embodiments, the compensation loop can be placed inseries arrangements at other intermediate regions of the circuit loop234 (see, e.g., FIG. 4C).

All references cited herein are hereby incorporated herein by referencein their entirety.

Having described preferred embodiments, which serve to illustratevarious concepts, structures and techniques, which are the subject ofthis patent, it will now become apparent to those of ordinary skill inthe art that other embodiments incorporating these concepts, structuresand techniques may be used. Accordingly, it is submitted that that scopeof the patent should not be limited to the described embodiments butrather should be limited only by the spirit and scope of the followingclaims.

1. A magnetic field sensor, comprising: a lead frame comprising: a baseplate, a ground pin coupled to the base plate, and a signal output pin;a first circuit board disposed over the lead frame, the first circuitboard comprising a conductive trace disposed thereon; a circuit diedisposed over the first circuit board, the circuit die comprising: asubstrate; a magnetic field sensing element disposed upon the substrateand configured to generate a magnetic field signal responsive to amagnetic field; an output circuit disposed upon the substrate, theoutput circuit comprising a circuit ground node and a circuit outputnode, wherein the output circuit is configured to generate an outputsignal at the circuit output node responsive to the magnetic fieldsignal; a ground circuit trace having first and second ends, wherein thefirst end of the ground circuit trace is coupled to the circuit groundnode; a ground bonding pad coupled to the second end of the groundcircuit trace; an output signal circuit trace having first and secondends, wherein the first end of the output signal circuit trace iscoupled to the circuit output node; and an output signal bonding padcoupled to the second end of the output signal circuit trace, whereinthe magnetic field sensor further comprises: a circuit loop comprising aconductive path between the ground pin and the signal output pin,wherein the circuit loop has a circuit loop interior area; a compensatedsignal output node coupled to the circuit output node; and a conductivestructure, comprising: a compensation loop coupled in a seriesarrangement with the circuit loop, wherein the compensation loopcomprises the conductive trace disposed upon the first circuit board,wherein the compensation loop has a compensation loop interior area,wherein the compensation loop interior area is selected to be related tothe interior area of the circuit loop, wherein a path traversing thecircuit loop in a direction from a first end of the series arrangementto a second end of the series arrangement has a circuit loop rotationdirection opposite from a compensation loop rotation directiontraversing the compensation loop along the same path, and wherein thecompensation loop interior area and the compensation loop rotationdirection are selected to result in a reduction of an overshoot or anundershoot of an output signal at the compensated signal output noderesulting from the circuit loop experiencing a rapid change in flux ofthe magnetic field.
 2. The magnetic field sensor of claim 1, wherein thecompensation loop is coupled between the circuit output node and thecompensated signal output node or the compensation loop is coupledbetween the between a loop termination node and the ground node.
 3. Themagnetic field sensor of claim 1, wherein the compensation loop interiorarea is selected to be approximately the same as the interior area ofthe circuit loop.
 4. The magnetic field sensor of claim 1, wherein thecompensation loop further comprises a conductive trace formed in one ormore metal layers of the circuit die, and wherein the compensated signaloutput node corresponds to the signal output pin.
 5. (canceled) 6.(canceled)
 7. The magnetic field sensor of claim 1, wherein thecompensation loop further comprises a portion of the lead frame, andwherein the compensated signal output node corresponds to the signaloutput pin.
 8. (canceled)
 9. (canceled)
 10. The magnetic field sensor ofclaim 1, further comprising a second circuit board, wherein thecompensation loop comprises a conductive trace formed on the secondcircuit board disposed such that a major surface of the second board isproximate to a major surface of the circuit die.
 11. (canceled)
 12. Themagnetic field sensor of claim 1, further comprising a second circuitboard, wherein the second circuit board comprises a current-carryingconductive trace configured to carry a current, wherein the magneticfield is generated in response to the current.
 13. The magnetic fieldsensor of claim 1, wherein the circuit loop comprises: a firstconductive path between the ground pin and the circuit ground node; asecond conductive path between the circuit ground node and the circuitoutput node; and a third conductive path between the circuit output nodeand the signal output pin.
 14. The magnetic field sensor of claim 1,further comprising a flux concentrator disposed proximate to the circuitdie.
 15. The magnetic field sensor of claim 14, wherein the fluxconcentrator comprises a donut shape having a notch in which the circuitdie is disposed, wherein the donut shape has in internal diameterselected to accept a current-carrying conductor configured to carry acurrent, wherein the magnetic field is generated in response to thecurrent.
 16. (canceled)
 17. The magnetic field sensor of claim 1,further comprising a current-carrying conductor configured to carry acurrent, wherein the magnetic field is generated in response to thecurrent.
 18. The magnetic field sensor of claim 17, further comprising aflux concentrator disposed proximate to the circuit die and proximate tothe current-carrying conductor.
 19. The magnetic field sensor of claim17, further comprising a U-shaped flux concentrator comprising two legsand an end region joining the two legs, wherein the circuit die and thecurrent-carrying conductor are disposed between the two legs of theU-shaped flux concentrator.
 20. The magnetic field sensor of claim 19,further comprising a molded package surrounding the circuit die, whereinthe current-carrying conductor comprises first and second major surfaceand first and second opposing joining surfaces at edges between thefirst and second major surfaces, wherein the current-carrying conductorcomprises a first notch in the first joining surface and a second notchin the second joining surface, wherein the molded package is disposed ina close fit arrangement within the first notch providing relativealignment of the circuit die to the current-carrying conductor, andwherein the end region of the U-shaped flux concentrator is disposedwithin the second notch in a close fit arrangement providing relativealignment of the U-shaped flux concentrator to the current-carryingconductor and to the circuit die.
 21. A method of compensating an outputsignal in a magnetic field sensor responsive to a magnetic field, themagnetic field sensor comprising a lead frame having a ground pin and asignal output pin, and a first circuit board disposed over the leadframe, wherein the first circuit board comprises a conductive tracedisposed thereon, wherein the magnetic field sensor also comprises acircuit die disposed over the first circuit board, wherein the circuitdie comprises magnetic field sensing element, and an output circuitcoupled to the magnetic field sensing element, wherein the outputcircuit comprises a circuit ground node and a circuit output node, themethod comprising: identifying a circuit loop in the magnetic fieldsensor comprised of a conductive path between the ground pin and thesignal output pin, wherein the circuit loop comprises a circuit loopinterior area; providing a compensated signal output node coupled to thecircuit output node; and providing a conductive structure, comprising:providing a compensation loop coupled in a series arrangement with thecircuit loop, wherein the compensation loop comprises the conductivetrace disposed upon the first circuit board, wherein the compensationloop has a compensation loop interior area, wherein the compensationloop interior area is selected to be related to the interior area of thecircuit loop, wherein a path traversing the circuit loop in a directionfrom a first end of the series arrangement to a second end of the seriesarrangement has a circuit loop rotation direction opposite from acompensation loop rotation direction traversing the compensation loopalong the same path, and wherein the compensation loop interior area andthe compensation loop rotation direction are selected to result in areduction of an overshoot or an undershoot of an output signal at thecompensated signal output node resulting from the circuit loopexperiencing a rapid change in film of the magnetic field.
 22. Themethod of claim 21, wherein the providing the compensation loopcomprises providing the compensation loop coupled between the circuitoutput node and the compensated signal output node or providing thecompensation loop coupled between the between a loop termination nodeand the ground node.
 23. The method of claim 21, wherein thecompensation loop interior area is selected to be approximately the sameas the interior area of the circuit loop.
 24. The method of claim 21,wherein the compensation loop furl comprises a conductive trace formedin one or more metal layers of the circuit die, and wherein thecompensated signal output node corresponds to the signal output pin. 25.The method of claim 21, wherein the compensation loop is comprised of aportion of the lead frame, and wherein the compensated signal outputnode corresponds to the signal output pin.
 26. The method of claim 21,wherein the compensation loop further comprises a conductive traceformed on a second circuit board disposed such that a major surface ofthe second circuit board is proximate to a major surface of the circuitdie.
 27. (canceled)
 28. The method of claim 21, further comprisingproviding a second circuit board proximate to a major surface of thecircuit die, wherein the second circuit board comprises acurrent-carrying conductive trace configured to carry a current, whereinthe magnetic field is generated in response to the current.
 29. Themethod of claim 21, wherein the circuit loop comprises: a firstconductive path between the ground pin and the circuit ground node; asecond conductive path between the circuit ground node and the circuitoutput node; and a third conductive path between the circuit output nodeand the signal output pin.
 30. The method of claim 21, furthercomprising placing a flux concentrator proximate to the circuit die. 31.The method of claim 30, wherein the flux concentrator comprises a donutshape having a notch in which the circuit die is disposed, wherein thedonut shape has in internal diameter selected to accept acurrent-carrying conductor configured to carry a current, wherein themagnetic field is generate in response to the current.
 32. (canceled)33. The method of claim 21, further comprising placing acurrent-carrying conductor configured to carry a current proximate tothe circuit die, wherein the magnetic field is generated in response tothe current.
 34. The method of claim 33, further comprising placing aflux concentrator proximate to the circuit die and proximate to thecurrent-carrying conductor.
 35. The method of claim 33, furthercomprising placing a U-shaped flux concentrator proximate to the circuitdie, the U-Shaped flux concentrator comprising two legs and an endregion joining the two legs, wherein the circuit die and thecurrent-carrying conductor are disposed between the two legs of theU-shaped flux concentrator.
 36. The method of claim 35, furthercomprising molding a molded package surrounding the circuit die, whereinthe current-carrying conductor comprises first and second major surfaceand first and second opposing joining surfaces at edges between thefirst and second major surfaces, wherein the current-carrying conductorcomprises a first notch in the first joining surface and a second notchin the second joining surface, wherein the molded package is disposed ina close fit arrangement within the first notch providing relativealignment of the circuit die to the current-carrying conductor, andwherein the end region of the U-shaped flux concentrator is disposedwithin the second notch in a close fit arrangement providing relativealignment of the U-shaped flux concentrator to the current-carryingconductor and to the circuit die.